Currently, liquid crystal displays (LCD) are most widely used display products on the market, production technologies are very mature, yield of products is high, production costs are relatively low, and market acceptance is high.
Most of the liquid crystal displays on the market are backlight type liquid crystal display devices, which include liquid crystal display panels and backlight modules. Usually a liquid crystal display panel is composed of a color filter (CF) substrate, an array substrate, and a liquid crystal and a sealing glue frame (i.e., sealant) which are located between the color filter substrate and the array substrate, wherein the CF substrate mainly includes a color filter layer containing a plurality of color resist units (RIG/B) that a light passes through the color resist units and transfers into a colored light, a black matrix (BM) that prevents light leakage at an edge of a pixel, and a spacer (photo spacer, PS) that maintains the cell thickness. A liquid crystal display controls orientation of the liquid crystal molecules through an electric field, thereby changing the polarization state of light emitting, and by utilizing a polarizer to achieve the penetration or blocking in a light path, for purpose of display.
Black photo spacer (BPS) is a new type of material that combines properties of conventional materials such as a better elastic restoring force and lower contamination of liquid crystal etc., and further has a higher optical density, and thus can achieve light barrier functions and thereby achieve effect of a black matrix. Currently, the BPS material is typically subjected to a photolithography process by using a multi-tone mask (MTM) which has a first patterning portion, a second patterning portion, and a third patterning portion having different light transmittances, for simultaneously and respectively, from the BPS material, at the same process, forming a main spacer, an auxiliary spacer, and a black matrix which have a height difference. FIG. 1 illustrates a film structure of a liquid crystal display panel in the conventional art. The transmittances of a multi-tone mask are respectively 100%, 30%, and 20%. A region of 100% transmittance corresponds to a main spacer region 110, a region of 30% transmittance corresponds to an auxiliary spacer area 111, a region of 20% transmittance corresponds to a black matrix 112, and these three structures are simultaneously formed by only one mask process. However, the MTM is complicated and expensive, and photolithography process of BPS is more difficult to adjust (need to give consideration to three different heights). Sub spacer (such as sub photo spacer, Sub PS) has a poor uniformity of height.